The present invention relates, in general, to data coding and, in particular, to a versatile system for Vertical Cavity Surface-Emitting Laser (VCSEL)-based bar code reading and scanning.
Bar code scanning is used in a vast array of commercial and industrial applications for convenient and efficient transfer of data and information. As requirements for faster processing of greater amounts of information have increased, efforts have been made to increase the efficiency and effectiveness of bar code scanning. In general, the amount and efficiency of information that a particular bar code can transfer is limited by the minimum required width of any individual bar (i.e. the pitch) in that code. As the minimum required bar width decreases (i.e. a smaller pitch is achieved), a greater number of bars can be coded in a given space. Thus, the amount of data coded in that given space, using small pitch bar coding, is increased, resulting in a more efficient system.
One major limitation on small pitch bar coding is the resolution of bar code reading systems. Where a bar code reading system lacks sufficient resolution to accurately distinguish small pitch bar codes, data transfer becomes unreliable and error prone. It is, thus, desirable to provide accurate and reliable small pitch bar code reading.
Conventional small pitch bar code reading and scanning systems generally use lasers in conjunction with optical lensing to generate and concentrate sufficient illumination on the media to be scanned and enable scanning of small pitch lines. Such systems usually suffer from optical inefficiency (due to the lensing), consume a relatively large amount of power (to compensate for the inefficiency), and are costly as a result of the extra componentry. Most conventional laser scanning systems also have a scan pattern that limits the total bar code width. One well-known variety of laser bar code scanner, sometimes referred to as free-space scanners (e.g., a retail cash register scanner), usually comprises a relatively large amount of componentry used to manipulate the laser beam back and forth across the bar code for proper reading. Some such systems employ lasers and multiple rotating mirrors to accomplish reading. These systems, while capable of reading small pitch bar codes, are very expensive and highly impractical for anything but retail applications. For most non-retail applications, a close-proximity bar code scanning system will suffice, rendering most conventional laser scanning systems highly inefficient.
Other conventional scanning and reading systems have utilized standard infrared and visible LEDs (light emitting diodes) as light sources for bar code scanning and reading. Again, such systems are limited as they require significantly more power (i.e. LED current) and optical lensing to provide sufficient illumination to produce a usable read signal. This results in increased space requirements and system costs. Also, such scanning systems are typically less accurate on small pitch bar codes, as they are generally limited by the size of the LED source, which is relatively large in comparison to the pitch of the bar code. Thus, LED-based scanning systems can also suffer from accuracy and reliability problems.
Further complicating the efficiency and performance of conventional bar code scanning, clocking systems have generally added to the complexity and cost of conventional systems while providing very restrictive clocking schemes and scenarios. Clocking is important, especially in bar code scanning, for accurate data transfer. Most bar code systems rely on manual movement of the bar code in relation to the scanner: either the bar code is passed over the stationary scanner, or the scanner is passed over the stationary bar code. Accurate interpretation of the bar code depends on the ability to differentiate individual bar widths. Unless a fixed, constant-rate scanning speed is guaranteed, some sort of reference signal (i.e. a clocking signal) must be utilized to time the scanning. Some conventional systems have relied on pre-set fixed-rate scanning, usually employing some sort of internal clocking system independent of the bar coding. This approach adds to system cost and complexity. Other conventional systems have relied on clocking signals read as part, or in conjunction with, a particular bar code. Typically, though, the relatively poor resolution of such systems either required a slow scan rate or tolerance for greater system unreliability.
The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
A versatile system for scanning or reading small pitch bar code and other similarly formatted data in a cost-effective, highly accurate and reliable manner while minimizing power consumption is now needed; providing readily adaptable close-proximity scanners and readers while overcoming the aforementioned limitations of conventional methods.
In the present invention, a VCSEL component and a detector are provided in close or predefined proximity to a media-reading area such that the detector receives diffuse angle reflections from the VCSEL component off a media being scanned; providing highly accurate small pitch scanning and reading in a highly cost-effective and readily adaptable manner.
The present invention provides a data scanning device comprising a housing having a scanning surface, a detector element disposed within the housing normal to the scanning surface, an aperture formed within the housing between the scanning surface and the detector element, and a laser source disposed within the housing adjoining the aperture.
The present invention also provides a diffuse reflective bar code reading system comprising a housing having a scanning surface, a detector element disposed within the housing in close proximity and normal to the scanning surface, a VCSEL component disposed within the housing in close proximity to the detector element and scanning surface, and an aperture formed within the housing between the scanning surface and the detector element.
The present invention further provides a method of optoelectronic data scanning, comprising the steps of providing a scanning surface having a target area, providing an optoelectronic detector disposed in close proximity and normal to the target area, providing a VCSEL component disposed in close proximity to the detector element and target area, adapted to source light to the target area from a diffuse angle, and receiving VCSEL-sourced light reflected from the target with the detector.
The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention or can be learned by practice of the present invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow.